When communication systems began providing the capability to transmit digital data along with voice information, systems which transmitted either voice or data were implemented. Systems which proclaimed the ability to transmit simultaneously both voice information and data were later developed. Typical methods in which both analog voice and data are transmitted include methods such as voice under data and voice over data. In either method, voice information and data are transmitted at two different frequencies. In voice over data, the voice spectrum is above the data spectrum. Similarly, in data over voice, the data spectrum is over the voice spectrum. In both methods, transmission speed of one type of transmission is sacrificed at the expense of transmission speed of the other type of transmission. Others have used protocols associated with digital telecommunicaton systems in which a data bit is substituted for the least significant voice bit in a technique known as "bit stealing". Such a protocol is taught by Larry Stagg in United Kingdom Pat. No. 2,063,018 for a synchronous data system. However, there still remains a need for a digital telephone which can simultaneously transmit digital voice information with asynchronous data at transmission rates approaching 9600 bits per second.